A process has recently been discovered for preparing polymerized metal oxide glasses of titanium or tantalum from solutions of their alkoxides. This process has the advantage that the coatings can be prepared at relatively low temperatures from solutions of carefully controlled compositions. The resulting coatings can be made to have a particular index of refraction by controlling the composition.
However, until now the compositions were limited to those containing principally titanium and tantalum alkoxides. It was not possible, for example, to prepare a polymeric alumina glass from an aluminum alkoxide, although alumina powders could be prepared from an aluminum alkoxide solution.